Multi-band log periodic antenna



p 1964 R. CARREL ETAL 3,150,376

MULTI-BAND LOG PERIODIC ANTENNA Filed April 3, 1964 2 Sheets-Sheet 1Beam Direction INVENTORS Roberf L. Carrel BY Paul E. Mayes Merriam,.Sml'f/I 8 Mars/m/l A T T OR/VE Y8 Sept. 22, 1964 Filed April 3, 1964Fig. 2

R. CARREL EIAL MULTI-BAND LOG PERIODIC ANTENNA 2 Sheets-Sheet 2INVENTORS Robert L. Carrel BY Paul- E. Mayes Merriam, Smith 8 Mar'sbb/lATTORA/EK? United States Patent 3,159,376 P/FJLTI-BAND LOG PERIODICANTENNA Robert L. Carrel, Richardson, Tex., and Paul E. hlayes,Champaign, lll., assignors to The University of Illinois Foundation, anen=profit organization of Illinois Filed Apr. 3, 1964, Ser. No. 357,22618 Claims. (Cl. 34-3-792.5)

This invention relates to antennas. More particularly it relates toantennas having unidirectional radiation patterns that are essentiallyindependent of frequency over wide bandwidths. Still more particularly,the antennas of the invention are designed to cover intermittent bandsof frequencies which cover a wide range from the lowest frequency bandto the highest.

In the copending application of Dwight E. l'sbell, Serial No. 26,589,filed May 3, 1960, and in application of the inventors herein, SerialNo. 59,671, filed September 30, 1960, now US. Patent No. 3,108,280,dated October 22, 1963, there are described certain antennas comprisingcoplanar arrays of dipoles or V-elements having unusually widebandwidths performance characteristics over which bandwidths theantennas are essentially frequency independent. These antennas haveinput impedances which are nearly constant with unidirectional patternsand directivities comparable to yagi arrays. As described in theapplications above named, the arrays comprise a number of elements whichmay be linear dipoles or" \/-elements, arranged in side-by-siderelationslnp in a plane. The lengths of the dipoles or the developedlengths of the V-elements (i.e., the length when the sides of theV-elements are rotated to form a linear dipole) and the spacing betweenadjacent dipoles or V-elements are designed to vary by approximatelychosen scale factors according to a definite mathematical formula, witheach of the elements being fed at its midpoint by a common feeder whichhas appropriate phasing between successive elements. The elements whichare used to make up the arrays vary progressively in length inaccordance with the scale factor selected.

in the linear dipole version, described in the aforementioned Isoellapplication, the length of the longest dipole element corresponds toabout /2 wavelength at the low frequency limit of the antennas effectiverange, While the shortest element has a length corresponding to about ofa wavelength at the upper frequency limit. On the other hand, theantennas described in the present inventors copending application,Serial No. 59,671, in which the elements are \.-shaped, have increaseddirectivity at frequencies above the /2 wavelength mode of operation andtherefore have eifective frequency ranges which are greater than thoseof a comparable linear di pole antenna.

The antennas of the instant invention are related to those describedabove, but difier therefrom in that the former are designed so thattheir efiective frequency range is not con inuous from the hi h limit tothe low limit but is rather broken up into a number of discrete bandswithin which bands the antenna performs satisfactorily.

' There are a number of instances in which antennas of type will befound particularly useful. For example, the frequencies assigned to VHFand UHF television transmission are divided into a number of discretefrequency bands. Thus, television channels 2, 3, and 4 of the lower VHFrange cover frequencies from 54 to 72 mcs., the mid-VHF band containingtelevision channels 5 and 6 extends from 76 to 88 mcs. and the upper VHFband, including television channels 7-13, extends from 174 to 216 'mcs.,while television channels 14-83 of the UHF band extend from 470 to 890mes.

An antenna made in accordance with the present in- 3,150,375 PatentedSept. 22, 1954 vention can effectively cover all of the above frequencybands, but not the intervening ranges between the bands of interest, andthis antenna is considerably smaller in overall size and weight and,therefore, less expensive than an antenna designed to cover continuouslythe entire range of television frequencies from 54 to 890 mcs.Furthermore, the directive gain increases in the higher modes which areused to cover the higher frequency bands, thus making more efiective useof the size of the structure.

Another application of the invention occurs in antennas designed for useby amateur radio operators whose transmissions are restricted by law tocertain frequency bands. The ham radio operator is, therefore,interested in an antenna which performs effectively in those ranges inwhich he is free to operate and which need not be effective in theintervening frequency bands. Such an antenna can also be made inaccordance with the invention in a smaller version than has beenheretofore possible, without sacrificing bandwidth or directivity.

The invention will be better understood from the following detaileddescription thereof taken in conjunction with the accompanying drawings,in which:

FIGURE 1 is a schematic plan view of an antenna made in accordance withthe principles of the invention;

FTGURE 2 is a perspective view of a practical antenna embodying theinvention; and

FIGURE 3 is a fragmentary view of an improved and preferred form of anantenna similar to that shown in FIGURE 2, as seen from a point directlyin front of and above the narrow end of the antenna.

Referring to FTGURE i, it will be seen that the antennas of theinvention are composed of a plurality of elements, which may eitherlinear dipoles, e.g., 11 and 12, or V-shaped elements, e.g., 13 and 14,or a combination of both as shown, arranged in side-by-siderelationship. The elements are arranged in a number of zones, or groups,e.g., A, B, C, and D. The distinguishing characteristic of the zonesfound in the antenna is the fact that the ends of the elements within azone fall on a pair of converging straight lines, as shown in thedrawing. It is also characteristic of the antennas of the invention thatthe converging lines defining the ends of the elements in a given zoneare not collinear with the corresponding converging lines associatedwith another zone of the antenna having the same type (i.e., lineardipole or V-element) of element. Thus, for example, since zones C and Dare both comprised of linear dipoles, the converging lines definingtheir terminals are not collinear. This is also true of zones A and Bwhich are also composed of similar elements. When adjacent zones arecomposed of dissimilar elements, however, as in the case of zones B andC, wherein B has V-elements and C has linear elements, the converginglines passing through the terminals of the elements of the zone may ormay not be collinear. Furthermore, the angle formed by these converginglines, e.g., oc in FIGURE 1, may or may not be equal for each zone,although all such angles preferably have values between about 20 andabout In the antenna shown in FIGURE 1, a is represented as the angledefined by the converging lines passing through the outer ends of theelements in zone A. This angle mi ht or might not be equal to that anglewhich would be formed on extending the lines passing through the ends ofthe elements of zone B to a meeting point. Similar considerations couldbe had relative to the angle which would result were a line to be drawnpast the ends of all elements of zones C and D.

It will be seen from FIGURE 1 that zones A and B are composed of aplurality of V -elements, each of which consists of a pair of arms,e.g., 16 and 17, defining an apex in'the middle of the V-element, saidV-elements arms on the same side of a line passing through the apexes'of the V-elements, are preferably substantially parallel to each other.

In a similar manner the linear dipoles which constitute zones C and D ofthe antenna of FIGURE 1 are each composed of a pair of arms, e.g., 18and 19, which are equal inlength and which are preferably substantiallyparallel to the corresponding arms of the other dipoles within the zone.V/ith respect to all zones, i.e., both those consisting of V-elementsand those formed of linear dipoles, it is preferred that the antenna besymmetrical about a line passing through the midpoints of the lineardipoles and the apexes of the V-elernents, respectively, as shown.

The antenna is fed at its narrow end from a conventional source ofenergy, depicted in FIGURE 1 by way of illustration only as alternator21, by means of a balanced feeder line consisting of conductors 22 and23. It will be seen that the crossed feeder lines 22 and 23 areftwistedbetween connections to consecutive or adjacent elements of the antenna.

The length of an element (dipole or V-element) in the antenna shown inFIGURE 1 is designated herein as L where n is used to designate anyelement in the zone. which is designated as X. Thus, for example, thelongest element in the antenna of FIGURE 1, which is the longest dipoleof group D, is designated as L 'rneaning element No. l of zone D. Thus,in general,

ment is taken to be the length which the arms of the a I V-element havewhen developed so that these arms are collinear. As shown, the length Lis the developed length of V-element 13. V

The lengths of the elements in the antennas of the invention, and thespacing between these elements are related by a scale factor 1- which isconstant within a given zone and is defined by the following equations:

where T is a constant having a value less than 1, L is the length of adipole (or the developed length of a V-element) in zone X of theantenna, L isthe corresponding length of the adjacent smaller element ingroup X, AS is the spacing between the element hav-' ing the length L,and the adjacent larger element in group X, and AS is the spacingbetween the element having the lengthL and the adjacent smaller elementin group X. 7

In the foregoing, it will be observed that the same scale factor, 1-,may be used to determine both dipole used. to determine the dipolelength and a scale factor 1 may be 'used to control spacing the dipolesections.

Each dipole and the feeder connecting thereto in the region between one.dipole pair and the next adjawnt' dipole pair maybe regarded as a cell.The lengths of dipoles-and the spacings then are so selected by thedetermined scale factors that the combinationofdipole lengths andspacings, when combined as, here described, provide the desiredsubstantially uniform wideband responses in qthe desired frequencyranges :AS'IIOIEQI above, the elements comprising the antennas *or theinvention may be either linear dipoles or 'V- elements. With respect tothe latter, the arms of the. individual V-elements are inclined to pointin the direction of decreasing element. size so that the apex of each ofthe V-elements points in a direction away from the angle formed by thelines passing through the extremities of the individual elements. Theangle, 11/, formed at the apexes of the V-elements by the arms thereof,preferably has a value between about 50 and 150.

It will be noted that in FIGURE 1 the angle cm is that formed by thelines passing through the extremities of the elements in zone A. In asimilar manner, although not shown in the drawing, the lines passingthrough the extremities of the elements in zones B, C, D, etc., could beextended to form similar angles oc et ca respectively. Each of theseangles a 1 a etc., may be equal to each other, and in the preferredembodiment of the antenna are equal, but this is not a necessary condi-.tion. In any event, it is preferred that these angles, whether or notthey are equal to each other, have values within the range from about 20to 100.

The advantages of the antennas of the invention stem from thediscoverythat when a given antennais in operation at a certain frequency thereare involved only a few of the elements of which the antenna is formed.

- It has been found possible, therefore, to remove from the antennastructure those elements which are not involved at this frequency andbring the adjacent parts of the antenna together to close the gap whichwould exist, and it has been further found that this modification of theantenna is possible without affecting the performance on either sideofthe excluded region. .Taking' the antenna of FIGURE 1 as an example,the element which would have formed the fourth element of Zone D is notrequired when the antenna is operated at a frequency which is dependenton the lengths of elements 1, 2 and 3. Accordingly, and since theantenna is not intended to operate at a frequency represented by thishypothetical V fourth element, the element can be omitted from theantenna with a. consequent saving" in size, weight, and

cost, without, however, adversely affecting the operation of theremaining elements in the antenna at their charac teristic frequencies.In a similar manner the elements which would normally have appeared inthe antenna between zones. A and B have been omitted. with no adverseeffects on the operation of the antenna at the frequenciescorrespon ingto the elements found in zones also permits more effective utilizationof a given antenna,

since the same structure can be used in several frequency modes toachieve coverage of different frequency bands.

In the case of an antenna zone or group consisting entirely of straightdipoles, the efiective frequency range of such a zone is that in whichthe low limit corresponds to the frequency at which. the large-stelement in the zone is about wavelength long, and the upper frequencylimit to the frequency at which the smallest dipole in the group I isaboutir wavelength long. In general, therefore, it may be said that thefrequency range of astraight dipole group of elements corresponds to themode of operation in which the lengths of the dipoles in the. group areabout a /2 wavelength long. As the frequency is raised above effectivelyat frequencies in which thedipoles are about wavelengths long (thewavelengthsmode), "7Q wave-l lengths long (the wavelengths mode), andsoon. A t I frequencies above the /Z wavelength mode, however, thepattern of a straight dipole group. becomes rnultilobed. and istherefore of limited *usefulness. Byinciining the arms of the dipoles toform l-ele mentgit has been found that a single lobe of improveddirectivity may be obtained as the frequency is raised from the /2waveiengh mode through the intervening ranges to the Wavelengths modeand beyond. For each mode or" operation there exists an optimum valuefor the angle 1, ranging from about 114 for the ,1) wavelength mode toabout 62 for the wavelengths mode. By using a comprorrn'se value for 1;this range, however, a zone of V-elements can be made to achieveacceptable performance over several modes of operation, therebyincreasing its elfective range. This result is possible since many ofthe elements forming the antenna array are used at more than onefrequency.

The construction of a practical antenna made in accordance with theinvention is shown in FIGURE 2. In this antenna the balanced lineconsists of two closely spaced and parallel electrically conductingsmall diameter tubes 24 and 26, to which are attached the arms whichform the Velements and the straight dipoles. it will be noted that eachof the arms making up one straight dipole, e.g., 29 and 31, or oneti-element, e.g., 2? 1 23, is connected to a different one of saidconductor as and 25. Moreover, considering either one of conductors 24-and 25, consecut ve arms along the length thereof extend in oppositedirections. It will be seen that this construction has the effect ofalternating the phase or" the connections between successive elements,as depicted schematically in FTGUR" 1. Although the elements of theantenna of liGUliE 2 are not precisely coplanar, difiering therefrom bythe distance between the parallel conductors 24 and 2:5, in practicedistance is usuall so that the arms of the elements are ubstautiallycoplanar and the advantages of the invention are maintained. in someinstances, however, it may be advantageous to bend the individual arms,e.g., 32 and 33 in FlGURE 3, close to the point of attachment to thefeeder lines 24' 26', so as to position all the arms in the same plane.The antennas of PL URES 2 and 3 may be conveniently fed by means of acoaxial cable, e.g., 34 and 34 positioned within conductor 26 or 26, theouter conductor of t e cable making electrical contact with theconductor 26 or 26 and the central conductor 36 or 35' of the cableextending to and electrical connection with conductor 2% or 24' asshown.

Li addition to type of construction shown in FIGURES 2 and 3, practicalantennas made in accordance with the invention can use a balanced feederline which is twisted between connections to successive dipoles or.i-eleznents.v Other suitable means for accomplishing the desiredphasing, such as transmission line loops or stubs, can also be used.

As an example of the invention, an antenna was constructed in a mannersimilar to that shown in FlGURE 3 containing two zones of elements, agroup of t -elements, such as group A in FIGURE 1, and a group of lineardipoles, such as group C. The antenna was made using 0.125" diametertubing for the balanced line and 0.050" diameter wire for the arms ofthe elements. The arms were soldered to the feeder line and the arraywas fed by a miniature coaxial cable inserted into one of the couductorsor" the balanced line. The antenna had a total of 12 elements, of which6 were contained in a zone of linear dipoles partially defined by7:9.98. The linear dipoles ranged in length from about 7.5 inches toabout 4.4 inches, the zone having a length of about 2 inches. Theantenna also contained a group of six V-elements O) ranging in developedlength from about 3.3 inches to about 2.6 inches, the group of elementshaving a length of about 1.1 inches, and being further defined by7:0.95. This antenna was a scale model of one designed to cover the 15meter, meter, 6 meter and 2 meter bands of amateur radio transmission.For the and 10 meter bands the antenna was operated in the /2 wavelengthmode as a linear dipole array. The 6 meter band was covered by thesf-elements of the antenna in the 1 the /2 Wavelength mode and the 2meter band was covered by the same ll-elements in the wavelength mode.This antenna was found to perform acceptably over this range, althoughthe performance in the 6 meter band was somewhat inferior to the otherbands which were covered.

' This deficiency, however, could have been rectified by provid ng anadditional large element in the group of V- elements.

it is believed evident from the above description that the antennas orthe invention can be designed to cover discrete frequency bands within aWide overall range as desired. By using the principles of the invention,the antenna can be made smaller in length and consequently cheaper toconstruct that has heretofore been possible, without, however,sacrificing performance within the desired frequency bands.

This application constitutes a continuation-in-part of U.S. patentapplication Serial No. 76,075, filed by the inventors herein named onDecember 15, 1960, now abandoned, and a continuation-in-part of US.patent application Serial No. 299,715, also filed by the inventorsherein named and carries a filing date of August 5, 1963, now abandoned.

The foregoing detailed description has been given for clearness ofunderstanchng only, and no unnecessary limitations should be understoodtherefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. A broadband unidi ectional an enna covering an intermittent range offrequencies comprising an array of a plurality of substantially coplanarelements, said elements being arranged in a plurality of zones, the endsof the elements in each of said zones falling on a pair of converginglines, the lines passing through the ends of the elements in any zonebeing non-collinear with at least one pair of the corresponding linesassociated with any other zone, the elements within any zone beingarranged in substantially parallel side-by-side relationship andprogressively increasing in length and spacing, the ratio of the lengthsof any two adjacent elements within any one of said zones being given bythe formula where L is the length or the larger of said adiacentelements, 1 is the length of the adjacent smaller element, and 'r is aconstant ha ing a value less than 1, the spacing between the elements ofany zone being given by the formula as, T

where A? is the spacing between the element having the 'ength L and theadjacent larger element, A5 is the spacing between the element havingthe length L and the adjacent smaller element, and T has thesignificance previously assigned, said elements being fed by a commonfeeder. which alternates in phase between successive elements.

2. The antenna of claim 1 in which the elements in at least one of saidzones are parallel dipoles.

3. The antenna of claim 1 in which the elements in at least one of saidzones are V-elements arranged in a herringbonelike arrangement, each ofsaid elements having a pair of equal arms defining an apex, the apexesof said i-elements lying on a straight line, the corresponding arms ofsaid-elements being parallel. V

4-. The antenna of claim 3 wherein the angle formed by the arms of anyV-element at the apex thereof has a value Within the range from about 50to about l50.

5. The antenna of claim 1 wherein the angles formed by the lines passingthrough ends of the elements in said 2 nee have values within the rangefrom about 20 to about and the values f the constant 1- associated withsaid zones lie within'the range from about 0.8 to about 0.95 V

6, A broadband unidirectional antenna covering an intermittent range offrequencies comprising an array of. a plurality of substantiallycoplanar conducting elements, said elements being arranged in aplurality of zones, the ends of the elements in each of said zonesfalling. substantially on a pair of converging lines, the lines passingsubstantially through the ends of the elements in any zone beingnon-collinear with at least one pair of the corresponding linesassociated with any other zone, the elements within anytzone beingarranged in substantially parallel side-by-side relationship andprogressively increasing in length, the ratio of the lengths of any twoadjacent elements within any one of said zones being determined by azonal scale factor established by the ratio of the length of oneconducting element to the length of the next adjacent and longerconducting element to establish the length scale factor, the spacing ofone conducting elementtto the next smaller element and the spacing ofthe same conducting element to the next longer conducting element witheach zone establishing the spacing scale factor, and Where each scalefactor in each zone is a constant, and a common two-conductor feederconnected to all of the elements with adjacent conductor elements beingCODIlEClEdiO different conductors of the feeder. V t

7. The antenna of claim 6 in whichthe elements in at least one of saidzones are parallel dipoles extending in a direction substantiallyperpendicular to the axis of the feeder. t

8; The. antenna of claim 67in which the elements in at least one of saidzones comprises vselements arranged in a herringbonelilre arrangement,each of said elements having a pair of equal arms defining an apex, theapeXes of said V-elements lying on a straight line, the correspondingarms of said elements being parallel, and in which at least one other.zone comprises dipole elements extending substantially normal to thefeeder axis. 7

' 9. An aerial system for wide-band use over selected intermittentfrequency ranges comprising a plurality of substantially coplanarelements arranged in a plurality of zones, at least one zone comprisinga plurality of herringbonelike conducting v-elements arrangedtoterminate in planar relationship, at least one other zone comprising aplurality of parallel dipoles, a ave-conductor balanced feeder connectedto the elements forming each zone at substantially'the inner endthereof, each two op posite V-elements and each two opposite paralleldipoles forming a pair constituting dipole halves, the connection fromeach adjacent conducting element of the dipole sections being to adifferent feeder, all of said elements being selectively spaced fromeach other, each element of each pair of conducting V-elements havingarms of substantially equal length substantially defining an apex withthe apexes of the plurality of V-elements all lying in subv stantially astraight line and terminating at the feeder, each of the paralleldipoles all lying in a common plane by-side relationship andprogressively differing length and also terminatingat the feeder, thesaid V-elements r and parallel dipoles. of, each pair being of dilferentelectrical lengths with successive V-elements and dipoles diffen'ng inelectrical length with respect to each other by substantially the samescale factor, each V -element and each dipole and 'the feeder betweensuccessive V-ele-' ments and dipoles constituting a cell, and theselective f spacings between'adjacent dipoles decreasing from one,

end to the other with the greater spacing being between the longestdipoles and being such that the combination 'of V-elements and dipolelengths and spacings provides a' substantially uniform wide-bandresponse over a plurality of selected frequency band's, the connectionbetween the band of higher frequencies, and means to connect the 7lengths and successive elements with eachzone differ in 1 feeder to anexternal circuit at a location substantially removed from the longest ofthe V-elements and dipole elements and in the direction of the smallestof the elements.

10. An aerial system for wide-band use covering intermittent frequencyranges comprising an array of a plurality of substantially coplanarconducting elements arranged in a plurality of zones, the conductingelements of each zone being similar, at least one zone comprising aplurality of herringbonelike conducting V-elements planarly arranged, atleast one other zone comprising a plurality of substantially straightand oppositely positioned conductor elements, a two-conductor balancedfeeder connected to each of said conducting elements at substantimy theinner end thereof, each two opposite V-elements forming a pairconstituting dipole halves, each two oppositely positioned elements alsoforming a pair constituting dipole halves, the connection from eachadjacent dipole section being to a different feeder, said -elernents ofthe zone being selectively spaced fromeach other, the elements of eachpair of V-elernents and each pair of oppositely'positioned elementshaving arms of substantially equal length, the V-elements of one zonesubstantially defining an apex with the apexes of the plurality ofV-elements all lying in substantially a straight line and terminating atthe feeder and the oppositely positioned elements of a second zone alsoterminating at l the feeder, the said dipoles of each pair being ofdilferent electrical lengths with successive dipoles in each zone dif- 1faring in electrical length with respect to each other by substantiallythe same scale factor, each dipole and the feeder between successivedipoles constituting a cell, and

as operation shifts from one band to an adjacent band of higherfrequencies, and means to connect the feeder to an external circuit at alocation substantially removed from the longest of the V-elements and inthe direction of the smallest of the J-elem'ents.

7 11. An aerial system for wide-band use covering intermittent frequencyranges comprising a plurality of pairs 7 of substantiallycoplanarconducting elements, the elemerits being arranged in a pluralityof 201165,, a twoconductor balanced feeder connected to each of saidelements atsubstantially the inner end thereof, the elements within eachzone being arranged in' substantially parallel sideand spacing, theconnection from each adjacent element being to a dilferent feeder, eachpair of elements having arms of substantially equal length, the ratio ofthe len ths, of any two adjace'ntelements within any one or" said zonesbeing determined and substantially proportioned by a length scale factorestablished by the ratio of the length of one of the conducting elementsto the length of the next adjacent longer conducting element so that theelements of each pair have different electrical electrical length withrespect to each adjacent element by substantially the same scale factor,each conductor w and the feeder between successive conductorsconstituting a cell, the ratio of the spacing of one 'lconduotingelement in each zone to the next smaller element and the spacing of thesme conductingelement in the said zone to the next longer conductingelement also establishing a spac'i ing scale factor, each or" the scalefactors having a value f of lessthan unity so that, the selectivespacings between adjacent conductors differ from on'e'end to the otherwith the greater spacing being between the longest conductors and beingsuch that the combination of conductor lengths and spacings provides asubstantially uniform wide-band response over the zone, the connectionbetween the conductors and the feeder being made in such a manner thatthe directive gain of the antenna increases as operation shifts from oneband to an adjacent band of higher frequencies, and means to connect thefeeder to an external circuit at a location substantially removed fromthe longest of the conducting elements and in the direction of thesmallest of the said elements.

12. The antenna claimed in claim 11 in which the conducting elements ofthe zones are arranged in V-formation with the open end of the V facedtoward the feeder connection.

13. The antenna claimed in claim 11 in which the conducting elements ofthe separate zones are parallel dipoles.

14. The antenna claimed in claim 11 in which the conducting elements ofeach zone are of similar form and the conducting elements of at leastone zone are arranged in V-formation with the open end of the V facedtoward the feeder connection and in which the conducting elements of atleast one other zone are parallel dipoles.

15. A broad band unidirectional antenna covering intermediate ranges ofa wide frequency spectrum comprising a multiplicity of substantiallycoplanar conductor elements, each conductor element forming half of adipole, the two elements of each dipole being of substantially the samelength, the several dipole elements being selectively spaced along anaxis and arranged in a plurality of separate zones, the electricallength of the dipoles decreasing with distance along the axis, theelectrical length of adjacent dipole elements of the separate zonesdiffering by a selected zone scale factor which is substantiallyconstant in each zone, the electrical length of each dipole of all zonesbeing approximately m odd multiple of a half-wave length at a frequencywithin the operating spectrum over which the antenna is to providemaximum response in each zone, a pair of feeder con ductors for feedingall of the dipole elements, one element of each dipole being connectedto one feeder conductor and the other element of each dipole beingconnected to the opposite feeder conductor, adjacent elements ofdifferent dipoles being connected to opposite feeder conductors so thatthe directional gain of the an tenna is maximum in the direction alongthe feeder from the end with longer dipoles toward the end with shorterdipoles and increases as the operation shifts from one frequency withinthe spectrum whereat the element lengths are approximately an oddintegral number of half-wave lengths to the next higher frequency rangewhere the element lengths are once more approximately an odd integralnumber of half-wave lengths, the ratio of the lengths of any twoadjacent dipole elements within any one of the zones being determined bythe zonal scale factor of substantially constant value within the zone,and means to connect the feeder conductors to an external circuit at alocation which is substantially removed from the longest dipole elementin the direction of the shortest dipole element.

16. The antenna claimed in claim 15 wherein the dipole elements of atleast one of the zones extend in a direction substantially perpendicularto the axis of the feeder conductors.

17. The antenna claimed in claim 15 in which the dipole elements of atleast one of the zones comprise V- shaped elements whose apexes lie onsubstantially a straight line and between which elements in the regionof the open portion of the V-formation there is an angular spacing inthe range from about and 18. The antenna claimed in claim 15 wherein thecorresponding dipole elements of each zone extend parallel to each otherand wherein certain of the dipoles extend substantially perpendicular tothe feeder and wherein other dipoles are V-shaped elements whose apexeslie on substantially a straight line with the angular spacing betweenthe elements of the open portion of the V-formation being within theangular limits of 50 and 150.

No references cited.

I UNITED-STATES PATENT O FFICE CERTIFICATE :OF CORRECTION Patent No, 3l5C 37 d September 22-1964 Robert. Carrel e'i ale It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

Column 2 line 33, after "may" insert be column 3, lines 14 to 46, theequation should appear as shown below instead of as in the patent:

' X X n n line 47 for "L read L' line lor "L read X "'s a ns 1 53 L llne 51 for A n rea n v lne g X X n n Y e for AS read AS 1) column 6 llne7 101 "large" read larger line 14 for "that" read than column 8 line 58strike out the comma Signed and sealed this 5th day of January 1965,

(SEAL) Attest:

ERNEST We SWIDER EDWARD Jr BRENNER Attesting Officer Commissioner ofPatents

1. A BROADBAND UNIDIRECTIONAL ANTENNA COVERING AN INTERMITTENT RANGE OFFREQUENCIES COMPRISING AN ARRAY OF A PLURALITY OF SUBSTANTIALLY COPLANARELEMENTS, SAID ELEMENTS BEING ARRANGED IN A PLURALITY OF ZONES, THE ENDSOF THE ELEMENTS IN EACH OF SAID ZONES FALLING ON A PAIR OF CONVERGINGLINES, THE LINES PASSING THROUGH THE ENDS OF THE ELEMENTS IN ANY ZONEBEING NON-COLLINEAR WITH AT LEAST ONE PAIR OF THE CORRESPONDING LINESASSOCIATED WITH ANY OTHER